Free space on disk has generally been managed in one of three ways. In a first approach, the allocation of a disk space for a file has been described by a linked list of sectors allocated to the file. In a second approach, a bitmap has been provided to monitor which sectors of disk space have been allocated. A bit is provided in the bitmap for each sector. The value of the bit associated with the sector specifies whether the sector has been allocated or not. In a third approach, allocation is performed on extents (i.e., a contiguous set of sectors on the disk). As such, space is allocated in ranges of adjacent sectors rather than in individual sectors.